1. Technical Field
The present disclosure generally relates to a mold and method for manufacturing an optical element utilizing the mold, and particularly to a lens mold and a method for manufacturing a lens utilizing the lens mold, wherein the lens is used as secondary optical element for an LED light source.
2. Description of the Related Art
LEDs have many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, faster switching, long term reliability, and environmental friendliness which have promoted their wide use as a light source.
The conventional LED generally generates a smooth round light field with a radiation angle of 90 degrees (−45 degrees to 45 degrees), wherein the light intensity is concentrated at a center of the conventional LED (i.e., 0 degree). The intensity of light emitted by the conventional LED is unevenly distributed, and will dramatically decrease when the radiation angle is beyond the range of 90 degrees. A lens which is used as a secondary optical element is usually matched with the LED to get even light outputs by refracting light at center to periphery.
A typical lens includes an incident surface, a bottom surface at a periphery of the incident surface and a light outputting surface opposite to the incident surface. To satisfy various illumination requirements, particularly to enable the light to be refracted at a large degree, the light outputting surface is usually configured with severely changing curvature for diffusing light towards different angles. However, due to the severely changing curvature of the outputting surface of the lens, part of the light will be totally reflected several times in the lens, which finally causes undesired light loss of the LED. As such, microstructures are conventionally formed at a bottom of the lens to avoid total internal reflection of light, thereby improving the light radiation efficiency of the LED.
When manufacturing lenses with a lens mold, the lens mold is specially designed according to desired microstructures of the lenses. However, the specially designed lens mold is unsuitable for manufacturing lenses with other different microstructures. So, when various types of lenses are manufactured, various different lens molds are needed, whereby a manufacturing cost of the lenses is high.
Therefore, it is desirable to provide a lens mold which can overcome the above-described problems.